The world is currently witnessing explosive growth in the demand for communications networks and systems and it is predicted that this demand will increase in the future. The demand for data services is growing at an ever increasing rate. Meeting these demands requires communication networks having higher bandwidth capabilities. In an effort to meet this demand, carriers must install facilities that are capable of carrying increasing amounts of data traffic. Manufacturers of network equipment attempt to keep up with the demand by developing equipment that can handle higher bandwidths.
In addition, much of the new bandwidth capacity being installed nowadays by carriers includes optical fiber networks. In particular, optical networks based on the SONET and SDH standards are commonly being installed. SONET/SDH optical networks are often configured to operate as ring structures since these types of networks exhibit improved performance.
A block diagram illustrating an example ring network is shown in FIG. 1. The ring network, generally reference 10, comprises a plurality of network devices 12 wherein each device or node is connected to its two neighbors via optical links 14. In the example shown herein, the ring network comprises four nodes labeled node A through node D. Each link comprises a bi-directional communications link. Note that an additional link may be used to connect each node thus creating a second inner ring. In this case, each ring handles traffic in a single direction, i.e. clockwise traffic and counterclockwise traffic.
The creation of large ring networks containing ten or more nodes is difficult since connections must be made to neighbors in either side of a node. Once a ring network is established and configured, insertion and deletion of nodes typically becomes very problematic. To insert or delete a node, the ring must be broken and new connections established to maintain the integrity of the ring.
One solution to this problem is to use a concentrator that is basically a network switching device whereby all the network devices (i.e. nodes) are connected in a physical star configuration to the concentrator. The concentrator emulates a ring structure internally by forwarding data from node to node around the ring via internal connections through the switch.
Although the use of a concentrator serves to simplify the physical cabling and connectivity needed to establish a ring network, the problem of configuring the internal connections in the concentrator remains. One approach is to have all internal routing configurations performed manually by the user. This approach permits the connection of nodes in any desired order but requires exact knowledge of the external connections, i.e. identification of ports, network devices and connections. Further, there is no detection of faulty wiring, connections or illegal routing. Any changes made later on, such as node addition, deletion and reordering, require the user to re-configure all the internal routing.
Another approach is to provide default routing whereby the internal routing is set to a default configuration. The external connections are then made so as to result in a logical ring. This method, however, does not permit any flexibility in reconfiguring the system and does not provide any fault wiring detection or prevention.
Thus, there is a need for a mechanism that can automatically detect and identify the nodes connected to the concentrator. Such a mechanism would be able to detect the insertion, deletion and modification of nodes attached to the concentrator. In addition, it is desirable to be able to automatically configure a ring network comprising the detected nodes.